21311003221 has 2 divisors, whose sum is σ = 21311003222. Its totient is φ = 21311003220.

The previous prime is 21311003149. The next prime is 21311003239. The reversal of 21311003221 is 12230011312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20740032196 + 570971025 = 144014^2 + 23895^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311003221 - 2⁷ = 21311003093 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21311003195 and 21311003204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21311003281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655501610 + 10655501611.

It is an arithmetic number, because the mean of its divisors is an integer number (10655501611).

Almost surely, 2^21311003221 is an apocalyptic number.

It is an amenable number.

21311003221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311003221 is an equidigital number, since it uses as much as digits as its factorization.

21311003221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21311003221 its reverse (12230011312), we get a palindrome (33541014533).

The spelling of 21311003221 in words is "twenty-one billion, three hundred eleven million, three thousand, two hundred twenty-one".